The present invention provides an external connection device and a host device that enable reduction in data transfer processing time between the host device and the external connection device by efficiently providing a processing command from the host device to the external connection device and provides a data communication system using such external connection device and host device.
An external connection device according to the present invention is connectable to a host device and includes a parameter register for storing a parameter, a command register for storing an operation control command provided from the host device, and a controller for referring to the operation control command stored in the command register and performing operation control specified by the operation control command. The parameter register and the command register are accessed from the host device on the basis of a transfer protocol command (TPC) issued from the host device. A command set of the TPC includes one or more register write commands for causing transmission of at least one of an arbitrary operation control command and an arbitrary parameter from the host device to the external connection device, storage of the transmitted operation control command into the command register, and/or storage of the transmitted parameter into the parameter register.
A host device according to the present invention is connectable to a host device to which an external connection device is connected. The host device includes transmission means for transmitting, to the external connection device, an operation control command indicating a command for performing operation control of the external connection device. The transmission means issues a transfer protocol command (TPC) to the external connection device to access the parameter register and the command register of the external connection device. A command set of the TPC includes one or more register write commands for transmission of at least one of an arbitrary operation control command and an arbitrary parameter from the host device to the external connection device, storage of the transmitted operation control command into the command register, and/or storage of the transmitted parameter into the parameter register.
A system according to the present invention includes the host device and the external connection device.
The foregoing aspects of the present invention will be further appreciated when considered with reference to the following detailed description and accompanying drawings.